Prenatal and early life exposures to ambient air pollution and development

Background: Residential proximity to major roadways, and prenatal exposures to particulate matter <2.5 μm (PM_2.5) and ozone (O₃) are linked to poor fetal outcomes but their relationship with childhood development is unclear. Objectives: We investigated whether proximity to major roadways, or prenatal and early-life exposures to PM_2.5 and O₃ increase the risk of early developmental delays. Study design: Prospective cohort. Settings: New York State excluding New York City. Participants: 4089 singletons and 1016 twins born between 2008 and 2010. Exposures: Proximity to major roadway was calculated using road network data from the NY Department of Transportation. Concentrations of PM_2.5 and O₃ estimated by the Environmental Protection Agency Downscaler models were spatiotemporally linked to each child's prenatal and early-life addresses incorporating residential history, and locations of maternal work and day-care. Outcomes: Parents reported their children's development at ages 8, 12, 18, 24, 30 and 36 months in five domains using the Ages and Stages Questionnaire. Generalized mixed models estimated the relative risk (RR) and 95% CI for failing any developmental domain per 10 units increase in PM_2.5 and O₃, and for those living <1000 m away from a major roadway compared to those living further. Models adjusted for potential confounders. Results: Compared to those >1000 m away from a major roadway, those resided 50–100 m [RR: 2.12 (1.00–4.52)] and 100–500 m [RR: 2.07 (1.02–4.22)] away had twice the risk of failing the communication domain. Prenatal exposures to both PM_2.5 and ozone during various pregnancy windows had weak but significant associations with failing any developmental domain with effects ranging from 1.6% to 2.7% for a 10 μg/m³ increase in PM_2.5 and 0.7%–1.7% for a 10 ppb increase in ozone. Average daily postnatal ozone exposure was positively associated with failing the overall screening by 8 months [3.3% (1.1%–5.5%)], 12 months [17.7% (10.4%–25.5%)], and 30 months [7.6%, (1.3%–14.3%)]. Findings were mixed for postnatal PM_2.5 exposures. Conclusions: In this prospective cohort study, proximity to major roadway and prenatal/early-life exposures to PM_2.5 and O₃ were associated with developmental delays. While awaiting larger studies with personal air pollution assessment, efforts to minimize air pollution exposures during critical developmental windows may be warranted.